JP4942415B2 - Paper making method - Google Patents

Description

The present invention relates to a papermaking method capable of improving yield, drainage, and squeezing without impairing the texture of a papermaking raw material containing a large amount of fine fibers and filler.

2. Description of the Related Art Conventionally, in a papermaking process such as coated base paper, PPC paper, high-quality paper, paperboard, and newsprint, various yielding systems have been used in order to improve the yield rate of fine fibers, fillers, and the like. For example, an addition formulation (Patent Document 1) in which a high molecular weight water-soluble cationic polymer is added before the shearing step and bentonite is added after the shearing step, and similarly, a water-soluble cationic polymer is added before the shearing step, As the second stage, a prescription in which anionic polymer microparticles are added is used (Patent Document 2). In recent years, it has been added to the conventional yield system to maintain the yield by increasing the proportion of waste paper and deinked pulp due to the increase in fine fibers in the papermaking raw material and the use ratio of fine calcium carbonate as filler. It was necessary to increase the rate and to increase the molecular weight of the first-stage cationic polymer. However, when the addition rate of the yield system is increased, a large amount of addition rate is required to maintain the yield, and the addition cost becomes enormous. On the other hand, if the cationic polymer has a high molecular weight, it is considered that excessive flocs are formed, and the paper quality, particularly the texture is deteriorated. Moreover, since an excessive floc takes in water excessively, the fall of the drainage in a wire part, the squeezing in a dryer part, and the fall of drying efficiency will be caused. For this reason, the conventional yield system cannot perform stable and productive operation.
JP-A-5-239800 JP-A-11-286890

It is an object of the present invention to provide a papermaking method for improving yield, drainage, water squeezing and productivity in a papermaking raw material containing a large amount of fine fibers and fillers without impairing the texture. To do.

As a result of detailed studies to solve the above problems, a dispersion polymerization method in which a water-soluble polymer dispersant coexists in an aqueous salt solution as a first step in the papermaking raw material before papermaking in the papermaking process. By forming a dispersion of fine particles having a particle diameter of 100 μm or less and adding a cationic or amphoteric water-soluble polymer having an intrinsic viscosity of 15 to 25 dl / g measured at 25 ° C. in a 1N NaCl aqueous solution, The present inventors have found that it is possible to improve the diffusibility into the slurry, improve the yield without impairing the texture, and improve the drainage and squeezability.

In the present invention the papermaking process, made from a dispersion of particle size 100μm following microparticles prepared by dispersion polymerization coexist soluble polymer dispersing agent to the salt solution in an aqueous salt solution to the paper stock prior to paper making, 1 A cationic or amphoteric water-soluble polymer having an intrinsic viscosity of 15 to 25 dl / g measured at 25 ° C. in a normal NaCl aqueous solution is added, and after passing through at least one shearing step, anionic inorganic fine particles, anionic organic fine particles and One or more selected from anionic polyacrylamide-based water-soluble polymers are added to the stock.

The additive formulation using the synthetic cationic or amphoteric water-soluble polymer used in the present invention can improve yield, drainage and water squeezing effect without impairing the texture, and can achieve reduction in addition cost and improvement in productivity. .

The cationic or amphoteric water-soluble polymer of the present invention was measured at 25 ° C. using a capillary viscometer with several water-soluble polymer dilutions diluted with 1N NaCl aqueous solution to a water-soluble polymer concentration of 0.1% by weight or less. Approximates the plot of reduced viscosity ηsp / c (unit: dl / g) to the formula ηsp / c = [η] + k × c (where c is the polymer concentration, the unit is g / dl, and [η] is the intrinsic viscosity) It is more preferable to use a water-soluble polymer having a coefficient k of 20 or less.

That is, simply increasing the molecular weight of the water-soluble polymer forms excessive flocs and deteriorates the paper quality, particularly the texture. Moreover, since an excessive floc takes in water excessively, the fall of the drainage in a wire part, the squeezing in a dryer part, and the fall of drying efficiency will be caused. Therefore, in the present invention, instead of using a polymer that is simply increased in molecular weight and greatly spread in an aqueous solution, the intermolecular force between side chains in the molecule is suppressed by crosslinking or suppressed by shrinkage or by crystallization. It is preferred to use polymers that tend to shrink due to.

This phenomenon is considered to be related to precipitation polymerization in an aqueous salt solution. That is, the polymer concentration becomes very high when insolubilized in a salt solution. As a result, the molecules are placed in a state where they are easily crystallized. In addition to this state, a small amount of a crosslinking agent coexists to carry out the polymerization, so that the concentration tends to be high locally, and it is considered that crystallization is promoted. Therefore, it is presumed that a part of the polymer is a molecule contracted in the solution by crystallization or covalent bonding by a crosslinking agent. Therefore, a water-soluble polymer having a coefficient k of 20 or less is considered to be in a more particle-like state.

For the above reasons, when a polymer in such a state is used as a yield improver in the paper industry, the paper-making raw material flocs are not enlarged and tightened to a small size, and the share is strong. Accordingly, not only the yield is improved, but also paper having a good texture can be produced. Further, the present invention is superior to a papermaking raw material containing a large amount of fine fibers in which the papermaking raw material contains a fine fiber content and a 200 mesh under fine content containing calcium carbonate is 45 to 85 mass percent with respect to the total dry solid content of the papermaking raw material. Show the effect.

The cationic or amphoteric water-soluble polymer of the present invention is an acrylamide-based water-soluble polymer, and is a polymer containing 5 to 50 mol% of a cationic monomer represented by the following structural formula.
General formula (1)
R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are an alkyl group or alkoxyl group having 1 to 3 carbon atoms, R ₄ is hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group or a benzyl group, A may be different, A is oxygen or NH, B is an alkoxyl or alkoxylene group having 2 to 4 carbon atoms, and X ₁ is an anion.

An example of the cationic water-soluble polymer is a copolymer of a cationic monomer and a nonionic monomer exemplified below. That is, the cationic monomer is a cationic vinyl monomer such as a salt of an inorganic acid or an organic acid such as dimethylaminoethyl (meth) acrylate or dimethylaminopropyl (meth) acrylamide, or quaternary ammonium by methyl chloride or benzyl chloride. A copolymer of salt and acrylamide. For example, as a monomer, (meth) acryloyloxyethyl trimethylammonium chloride, (meth) acryloyloxy 2-hydroxypropyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzyl Examples include ammonium chloride, (meth) acryloyloxy 2-hydroxypropyldimethylbenzylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium chloride, and the like. Also, diallylammonium salts such as dimethyldiallylammonium chloride can be used.

The amphoteric water-soluble polymer can be synthesized by copolymerization of an anionic vinyl monomer and the cationic monomer. Anionic vinyl monomers are acrylamide 2-methylpropane sulfonic acid, styrene sulfonic acid, (meth) allyl sulfonic acid, vinyl sulfonic acid, (meth) acrylic acid, maleic acid or itaconic acid. Use to copolymerize.

Further, nonionic monomers may be copolymerized with these ionic monomers. Examples of such nonionic monomers include (meth) acrylamide, N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, N -Vinylpyrrolidone, N-vinylformamide, N-vinylacetamidoacryloylmorpholine, acryloylpiperazine and the like. Of these, acrylamide is most preferred.

The molar% of the cationic monomer and the nonionic monomer of these cationic water-soluble polymers is 5 to 50 mol% of the cationic monomer and 50 to 95 mol% of the nonionic monomer, Preferably they are 10-40 mol% of cationic monomers, and 60-90 mol% of nonionic monomers.

Further, the mol% of the cationic monomer and the anionic monomer of the amphoteric water-soluble polymer is 5 to 50 mol% of the cationic monomer and 5 to 50 mol% of the anionic monomer, preferably cation 10 to 40 mol% of the ionic monomer and 5 to 50 mol% of the anionic monomer.

The cationic or amphoteric water-soluble polymer used in the present invention constitutes a dispersion of fine particles having a particle size of 100 μm or less produced by a dispersion polymerization method in which a polymer dispersant soluble in the aqueous salt solution coexists in the aqueous salt solution. ing.

A cationic or amphoteric water-soluble polymer comprising a dispersion in brine can be produced by the following operation. That is, a water-soluble polymer comprising a polymer fine particle dispersion dispersed in an aqueous salt solution can be produced by Japanese Patent Application Laid-Open No. 62-15251. In this method, a cationic monomer or a cationic monomer and a nonionic monomer are stirred in a salt aqueous solution in the presence of a dispersant composed of an ionic polymer soluble in the salt aqueous solution. It consists of a dispersion of polymer fine particles having a particle size of 100 μm or less. As the dispersant made of an ionic polymer, a homopolymer of dimethyldiallylammonium chloride or (meth) acryloyloxyethyltrimethylammonium chloride or a copolymer with a nonionic monomer is used. The inorganic salts constituting the aqueous salt solution are more preferably polyvalent anion salts, and sulfates or phosphates are suitable. Specifically, ammonium sulfate, sodium sulfate, magnesium sulfate, aluminum sulfate, ammonium hydrogen phosphate, hydrogen phosphate Examples thereof include sodium and potassium hydrogen phosphate, and these salts are preferably used as an aqueous solution having a concentration of 15% or more.

The cationic or amphoteric water-soluble polymer of the present invention has an intrinsic viscosity of 15 to 25 dl / g measured at 25 ° C. in a 1 N NaCl aqueous solution, and an intrinsic viscosity in this range is preferably used. If the intrinsic viscosity is less than 15 dl / g, the yield tends to decrease, and if it is more than 15 to 25 dl / g, the formation is lowered, which is not preferable.

The cationic or amphoteric water-soluble polymer of the present invention is obtained by diluting several water-soluble polymer dilutions diluted with 1N NaCl aqueous solution to a water-soluble polymer concentration of 0.1% by weight or less at 25 ° C. using a capillary viscometer. A plot of the measured reduced viscosity ηsp / c (unit: dl / g) is expressed as ηsp / c = [η] + k × c (where c is the polymer concentration, the unit is g / dl, and [η] is the intrinsic viscosity). It is more preferable to use a water-soluble polymer having a coefficient k value of 20 or less when approximated.

In other words, as described in the background art, simply increasing the molecular weight of the water-soluble polymer forms excessive flocs, deteriorating paper quality, particularly texture. Moreover, since an excessive floc takes in water excessively, the fall of the drainage in a wire part, the squeezing in a dryer part, and the fall of drying efficiency will be caused. Therefore, in the present invention, instead of using a polymer that is simply increased in molecular weight and greatly spread in an aqueous solution, the intermolecular force between side chains in the molecule is suppressed by crosslinking or suppressed by shrinkage or by crystallization. It is preferred to use polymers that tend to shrink due to.

This phenomenon is considered to be related to precipitation polymerization in an aqueous salt solution. That is, the polymer concentration becomes very high when insolubilized in a salt solution. As a result, the molecules are placed in a state where they are easily crystallized. In addition to this state, a small amount of a crosslinking agent coexists to carry out the polymerization, so that the concentration tends to be high locally, and it is considered that crystallization is promoted. Therefore, it is presumed that a part of the polymer is a molecule contracted in the solution by crystallization or covalent bonding by a crosslinking agent. Therefore, a water-soluble polymer having a coefficient k of 20 or less is considered to be in a more particle-like state.

For the above reasons, when a polymer in such a state is used as a yield improver in the paper industry, the paper-making raw material flocs are not enlarged and tightened to a small size, and the share is strong. Accordingly, not only the yield is improved, but also paper having a good texture can be produced.

The addition rate of the synthetic cationic or amphoteric water-soluble polymer used in the present invention is 0.001 to 0.1% by weight, preferably 0.005 to 0.1% by weight, based on the total stock. If it is 0.001% by weight or less, the effect may not be exhibited, and if it is 0.1% by weight or more, the improvement of the effect is not observed, which is uneconomical.

When the cationic or amphoteric water-soluble polymer of the present invention is added, it exhibits good particle dispersibility and good dispersibility, impairing diffusion to papermaking stocks containing a large amount of fine fibers or a large amount of fine calcium carbonate. The addition is efficient. Moreover, since it is not added locally, a nonuniform huge floc is not formed and the fall of a texture is suppressed.

After the addition of the first-stage cationic or amphoteric water-soluble polymer, the anionic inorganic fine particles or the anionic organic fine particles are added through at least one shearing process to further improve the yield, drainage and water squeezability. The effect is improved. In addition, in order to maintain the yield effect, drainage and squeezing effect at the addition rate required by one liquid, the total amount of the addition ratio can be lowered by adding two liquids, and the addition cost can be suppressed and the economy is reduced. Is.

The papermaking method of the present invention uses bentonite or colloidal silica as anionic inorganic fine particles as the second stage after at least one shearing step after addition of the water-soluble polymer. The addition rate is 0.001 to 0.5% by weight, preferably 0.005 to 0.1% by weight, based on the papermaking raw material.

In the papermaking method of the present invention, after addition of the water-soluble polymer, at least one shearing process is performed, and the second stage is acrylamide water-swellable fine particles or non-acrylamide water-insoluble fine particles. Acrylamide-based water-swellable fine particles are water-insoluble water-swellable fine particles having a high degree of crosslinking, which are synthesized by water-in-oil emulsion polymerization in which acrylamide is present in the presence of an anionic monomer and a crosslinkable monomer. The fine particles have a particle size of 1000 nm or less, preferably 200 nm or less before water swelling. On the other hand, non-acrylamide water-insoluble fine particles are water-insoluble monomers, that is, water-insoluble anionic fine particles synthesized by oil-in-water emulsion polymerization in which styrene or (meth) acrylic acid esters are present in the presence of an anionic monomer. is there. The fine particles preferably have a particle size of 200 nm or less. The addition rate of these anionic organic fine particles is 0.001 to 0.5% by weight, preferably 0.005 to 0.1% by weight, based on the total stock.

Furthermore, in the papermaking method of the present invention, after addition of the water-soluble polymer, an anionic polyacrylamide-based water-soluble polymer is added as the second stage through at least one shearing step. The anionic polyacrylamide-based water-soluble polymer is as follows. That is, homopolymers such as vinyl sulfonic acid, vinyl benzene sulfonic acid or 2-acrylamide 2-methylpropane sulfonic acid, methacrylic acid, acrylic acid, itaconic acid, maleic acid or p-carboxystyrene, or two or more copolymerizable It is a copolymer of Moreover, the copolymer with another nonionic monomer may be sufficient. For example, (meth) acrylamide, N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide The copolymerization with these 1 type (s) or 2 or more types is possible.

The composition of the monomer (mixture) to be polymerized is 5 to 100 mol% anionic monomer and 0 to 95 mol% acrylamide. The molecular weight of these anionic polymers is 1 million to 20 million, preferably 5 million to 15 million. The addition rate is 0.001 to 0.1% by weight, preferably 0.005 to 0.05% by weight, based on the total stock.

The target paper is not particularly limited, and can be applied to any paper. However, in particular, a newspaper paper containing a large amount of fine fibers, which is difficult to be effective in a conventional yield system, and a coating in which calcium carbonate is often used as a filler. The effect is more exerted on engineering paper and PPC paper. That is, the content of the 200-mesh under fine component containing fine fiber content + calcium carbonate is about 45-85% for newsprint. In the case of coated base paper and PPC paper, it is about 40 to 75%.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Synthesis Example 1) A four-neck 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with 117.7 g of deionized water, 84.1 g of ammonium sulfate, and 80 wt% acryloyl as a cationic monomer. 17.7 g of oxyethyltrimethylammonium chloride (DMQ) and 80% by weight of acryloyloxyethyldimethylbenzylammonium chloride (hereinafter DMABC) 6.2 g, 51.9 g of 50% by weight acrylamide (hereinafter AAM), acryloyloxy as a dispersant 22.5 g of ethyltrimethylammonium chloride homopolymer (20% by weight solution, viscosity 6450 mPa · s) was charged. Thereafter, nitrogen was introduced from the nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature was adjusted to 35 ± 2 ° C. using a constant temperature water bath. 30 minutes after nitrogen introduction, 0.45 g of 1% by weight aqueous solution of 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride as an initiator (as a monomer) 100 ppm) was added to initiate the polymerization. 0.45 g of the initiator was added after 6 hours from the start of polymerization while maintaining the internal temperature at 35 ± 2 ° C., and the reaction was further completed for 10 hours. This obtained dispersion is designated as prototype 1. The DMQ / DMABC / AAM molar ratio was 16/4/80, and the dispersion viscosity was 540 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. In addition, the reduced viscosity of each solution diluted to a polymer concentration of 0.02 g / dl, 0.04 g / dl, and 0.06 g / dl in a 1N NaCl aqueous solution using a Canon Fenceke viscometer is measured at 25 ° C. The coefficient k and the intrinsic viscosity were calculated. The results are shown in Table 1.

(Synthesis Example 2) In the same apparatus as in Synthesis Example 1, 112.2 g of deionized water, 89.3 g of ammonium sulfate, 13.5 g of 80 wt% DMQ and 80 wt% methacryloyloxyethyl trimethyl ammonium chloride (hereinafter referred to as cationic monomers) DMC) 9.7 g, 50 wt% AAM 52.9 g, and 22.5 g of acryloyloxyethyltrimethylammonium chloride homopolymer (20 wt% solution, viscosity 6450 mPa · s) as a dispersing agent were charged in the same manner as in Example 1. Reacted in the way. The obtained dispersion is referred to as trial production 2. The molar ratio of DMQ / DMC / AAM was 12/8/80, and the viscosity of the dispersion was 720 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the reduced viscosity was measured in the same manner as in Example 1, and the coefficient k and the intrinsic viscosity were calculated. The results are shown in Table 1.

(Synthesis Example 3) In the same apparatus as in Synthesis Example 1, 112.3 g of deionized water, 89.3 g of ammonium sulfate, 2.7 g of 60% by weight acrylic acid (hereinafter AAC), 11.2 g of 80% by weight DMQ as a cationic monomer And 12.5 g of 80 wt% DMC, 50.9 g of 50 wt% AAM, and 22.5 g of acryloyloxyethyltrimethylammonium chloride homopolymer (20 wt% solution, viscosity 6450 mPa · s) as a dispersing agent, respectively, It reacted in the same way. The resulting dispersion is referred to as prototype 3. The molar ratio of AAC / DMQ / DMC / AAM was 5/10/10/75, and the viscosity of the dispersion was 870 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the reduced viscosity was measured in the same manner as in Example 1, and the coefficient k and the intrinsic viscosity were calculated. The results are shown in Table 1.

(Synthesis Example 4) 111.9 g of deionized water, 89.3 g of ammonium sulfate, 80 wt% DMQ 16.0 g and 50 wt% AAM 37.5 g as a cationic monomer, and acryloyloxy as a dispersing agent 15.8 g of ethyl trimethylammonium chloride homopolymer (20% by weight solution, viscosity 6450 mPa · s) was charged. Thereafter, nitrogen was introduced from the nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature was adjusted to 35 ± 2 ° C. using a constant temperature water bath. 30 minutes after nitrogen introduction, 0.45 g of 1% by weight aqueous solution of 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride as an initiator (as a monomer) 100 ppm) was added to initiate the polymerization. The internal temperature was maintained at 35 ± 2 ° C., and 2 hours after the start of polymerization, 3.4 g of 80 wt% DMQ, 8.0 g of 50 wt% AAM, acryloyloxyethyltrimethylammonium chloride homopolymer as a dispersant (20 wt% liquid, viscosity 6450 mPa · s) 3.4 g of the mixture was added. After another 2 hours, a mixture of 3.4 g of 80 wt% DMQ, 8.0 g of 50 wt% AAM, and 3.4 g of acryloyloxyethyltrimethylammonium chloride homopolymer (20 wt% liquid, viscosity 6450 mPa · s) as a dispersant was added. . After 8 hours from the start of polymerization, 0.45 g of the above initiator was added, and the reaction was further completed for 10 hours. During the polymerization reaction, nitrogen was continuously introduced from the nitrogen introduction tube. This dispersion is designated as prototype 4. The DMQ / AAM molar ratio was 20/80, and the dispersion viscosity was 960 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the reduced viscosity was measured in the same manner as in Example 1, and the coefficient k and the intrinsic viscosity were calculated. The results are shown in Table 1.

(Comparative Synthesis Example 1) The same monomer composition as in Example 4 was not divided and charged, but the entire amount was charged all at once to initiate polymerization. Two hours after the start of the polymerization, the viscosity of the reaction solution was remarkably increased and stirring was impossible, and the whole amount became a lump and could not be obtained as a fluid dispersion.

(Comparative Synthesis Example 2) Similar to Comparative Example 1, the same monomer composition as in Example 4 was divided and charged all at once, and isopropyl alcohol as a chain transfer agent was added to the monomer 0.5. %added. That is, 111.9 g of deionized water, 89.3 g of ammonium sulfate, 80 wt% DMQ 22.8 g and 50 wt% AAM 5305 g as a cationic monomer, and acryloyloxyethyltrimethylammonium chloride homopolymer (20 wt% solution, Viscosity 6450 mPa · s) 22.5 g, 0.23 g of isopropyl alcohol as a chain transfer agent were charged, and reacted in the same manner as in Example 1. The obtained dispersion is referred to as Comparative 2. The DMQ / AAM molar ratio was 20/80, and the viscosity of the dispersion was 1020 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the reduced viscosity was measured in the same manner as in Example 1, and the coefficient k and the intrinsic viscosity were calculated. The results are shown in Table 1.

(Comparative Synthesis Example 3) 0.23 g (0.5% monomer) of isopropyl alcohol was further added as a chain transfer agent to the same monomer composition as in Example 1, and reacted in the same manner as in Example 1. The obtained dispersion is designated as Comparative Example 3. The DMQ / DMABC / AAM molar ratio was 16/4/80, and the dispersion viscosity was 390 mPa · s. As a result of microscopic observation, the particles were found to be 1 to 50 μm. Further, the reduced viscosity was measured in the same manner as in Example 1, and the coefficient k and the intrinsic viscosity were calculated. The results are shown in Table 1.

(Table 1)
DMQ: acryloyloxyethyltrimethylammonium chloride DMC: methacryloyloxyethyltrimethylammonium chloride ABC: acryloyloxyethyldimethylbenzylammonium chloride, AAC: acrylic acid, AAM: acrylamide, numerical unit Dispersion viscosity: mPa · s, inherent Viscosity (in 1N NaCl aqueous solution): dl / g

A yield measurement test was performed using a dynamic jar tester. Use 200 mesh wire. The raw material used was a newspaper papermaking raw material with a solid content of 0.9% by mass and a 200 mesh under 73.0% (fine content; fine fiber content + filler calcium carbonate). The physical properties of the papermaking raw materials are pH 7.3, Whatman No. The required amount of cation of 41 filter paper filtrate was 0.0249 meq / L, and the turbidity was 10 NTU. The required amount of cation was PCD-03 type manufactured by Mutech, and the turbidity was DR-2100 type manufactured by HACH. SZP according to SZP-06 type manufactured by Mutek was -7.3 mV. As a first liquid, Sample-1 was added at 150 ppm with respect to the solid content of the paper stock, stirred at 1200 rpm for 20 seconds, and then dispersed in an anionic polyacrylamide salt water dispersion (acrylamide / sodium acrylate = 70 / 30 copolymer, molecular weight 10 million) (sample-5) was added at 150 ppm with respect to the solid content of the paper stock, stirred for 10 seconds, and the filtrate was collected, ADVANTECNo. After filtering with 2 filter papers, SS was measured, and the total yield was measured. Then, the filter paper was ashed at 525 ° C. for 2 hours, and the ash yield was measured.

A similar test was performed on Sample-2 to Sample-4 in combination with an anionic polyacrylamide salt water dispersion or bentonite (addition amount of 1500 ppm). These results are shown in Table 2.

(Comparative Test 1) A similar test was carried out using Comparative-2 to Comparative-3. The results are shown in Table 2.

In Examples 1-1 to 1-4 using Sample-1 to Sample-4 of the present invention, the total yield rate and the ash content yield rate were improved as compared with Comparative Tests 1-2 to 1-3. Can be confirmed.

(Table 2)
Cation / amphoteric; addition rate 0.015% (vs dry paper raw material), sample-5; addition rate 0.015% (vs dry paper raw material), BT (bentonite); 0.15% (vs dry paper raw material)

Using the same paper material as in Example 1, a freeness and texture measurement test using a dynamic drainage tester DDA (Dynamic Drainage Analyzer, manufactured by Matsubo) was performed. The papermaking material is put into a DDA stirring tank with a 315 mesh wire at the bottom. Sample-2 to Sample-4 were added at 150 ppm with respect to the solid content of the stock as the first solution, stirred for 20 seconds at a stirring speed of 1000 rpm, and then dispersed in anionic polyacrylamide salt water (acrylamide / acrylic acid) as the second solution. Sodium = 70/30 copolymer, molecular weight 10 million) (Sample-5) was added to the solid content of the paper at 150 ppm, stirred for 10 seconds, and then the paper was sucked under a reduced pressure of 300 mBar and placed on the wire. The drainage time at the time when the sheet was formed and the final pressure reduction degree of the formed sheet (numerical values related to the formation of the formed paper) were measured, and the results are shown in Table 3.

(Comparative Test 2) Using the same paper material as in Example 1, a freeness and texture measurement test using a dynamic drainage tester DDA was performed under the same test conditions. As a first solution, comparisons 2 to 3 were added at 150 ppm with respect to the solid content of the paper stock, and a second solution was an anionic polyacrylamide salt water dispersion (acrylamide / sodium acrylate = 70/30 copolymer, molecular weight). 10 million) (Sample-5) was added to 150 ppm of the solid content of the paper, or 1500 ppm of bentonite was added to the solid content of the paper, and the drainage time and the final pressure reduction were measured. Table 3 shows.

(Table 3)

It can be confirmed that Sample-1 to Sample-4 of the present invention have a shorter drainage time and better drainage performance than Comparative-2 to Comparative-3. In addition, the final degree of decompression is an index of the texture, and it can be determined that the texture is better as the numerical value is higher. Since Sample-1 to Sample-4 are comparable to Comparative-2 to Comparative-3, it means that drainage performance is improved without impairing the texture. This is because the drainage of Sample-1 to Sample-- is improved compared to Comparative-2 to Comparative-3, but the final decompression degree is about the same because the formed flocs are fine and do not form excessive flocs. Suggest.

A yield test was carried out using the same papermaking raw materials and conditions as in Example 1. Sample-1 to Sample-4 were added at 150 ppm with respect to the solid content of the paper as the first solution, stirred for 20 seconds at a stirring speed of 1000 rpm, and then a single solution consisting of 93 mol% styrene and 7 mol% methacrylic acid as the second solution. The polymer mixture was polymerized by forming a microemulsion with an anionic polymer surfactant and a polyoxyethylene hydrophilic surfactant to polymerize the 150 nm particle size anionic polymer microparticles (Sample-6). After adding 150 ppm to the solid content of the paper and stirring for 10 seconds, the filtrate was collected, and ADVANTEC No. After filtering with 2 filter papers, SS was measured, and the total yield was measured. Then, the filter paper was ashed at 525 ° C. for 2 hours, and the ash yield was measured. The results are shown in Table 4.

(Comparative Test 3) A similar test was performed using Comparative-2 to Comparative-3. The results are shown in Table 4.

A test similar to that of Example 4 was performed using water-swellable polyacrylamide particles as anionic polymer microparticles. That is, a monomer mixture consisting of 88 mol% acrylamide, 12 mol% acrylic acid, and 0.5% by mass of methylenebisacrylamide was formed into a water-in-oil emulsion using a sorbitan oleate-based hydrophobic surfactant, Water-insoluble particles obtained by polymerization (particle size after dispersion in water of about 700 nm) (Sample-7) were used. The results are shown in Table 4.

(Comparative Test 4) A similar test was performed using Comparative-2 to Comparative-3. The results are shown in Table 4.

(Table 4)

Claims (5)

At the time of papermaking in the papermaking process , 5 to 50 mol% of a cationic monomer represented by the following general formula (1) as a first step and (meth) acryloyloxy for the purpose of improving yield and / or drainage in the papermaking raw material A particle size of 100 μm produced by a dispersion polymerization method in which a cationic or amphoteric water-soluble polymer containing 0 to 4 mol% of ethyldimethylbenzylammonium chloride coexists with a polymer dispersant soluble in the aqueous salt solution in the aqueous salt solution. made from a dispersion of the following microparticles, through in 1N NaCl aqueous solution, adding the cationic or amphoteric water-soluble polymer is intrinsic viscosity measured at 25 ° C. is 15~25dl / g, the at least one shear steps In the second stage, anionic inorganic fine particles, anionic organic fine particles and anionic polyacrylamide water-soluble polymers Paper making method characterized by adding one or more kinds in stock selected from.
General formula (1)
R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are an alkyl group or alkoxyl group having 1 to 3 carbon atoms, R ₄ is hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group or a benzyl group, A may be different, A is oxygen or NH, B is an alkylene group or alkoxylene group having 2 to 4 carbon atoms, and X ₁ is an anion. Reduced viscosity ηsp obtained by measuring several water-soluble polymer dilutions obtained by diluting the cationic or amphoteric water-soluble polymer with a 1N NaCl aqueous solution to a water-soluble polymer concentration of 0.1% by weight or less with a capillary viscometer at 25 ° C. / C (unit: dl / g) is a coefficient when approximating the equation of ηsp / c = [η] + k × c (where c is the polymer concentration, the unit is g / dl, and [η] is the intrinsic viscosity) The papermaking method according to claim 1, wherein the value of k is 20 or less. Papermaking method according to any one of claims 1-2, characterized in that the anionic inorganic particles are bentonite or colloidal silica. The anionic organic particles, papermaking method according to any one of claims 1-2, characterized in that the acrylamide-based water-swellable particulate or non-acrylamide based water-insoluble particles. 2. The papermaking method according to claim 1, wherein the papermaking raw material has a fine content of 200 mesh under containing fine fiber and calcium carbonate in an amount of 45 to 85 mass percent based on the total dry solid content of the papermaking raw material.